Emerging evidence demonstrates that elevated environmental manganese (Mn) exposure is associated with cognitive and behavioral deficits in children. However, up to now, studies in children have only been focused on exposure via ingestion pathways, although occupational research in adults has established that Mn exposure via inhalation poses a more significant risk for cognitive and motor effects than exposure via ingestion. We will assess the neurodevelopmental effects of airborne Mn exposure in 11-13 year old children living in areas impacted by current or past ferroalloy industries. We will examine 750 children across three well- characterized study sites in the province of Brescia, Italy, that differ in history of ferroalloy plant activity: 1) Bagnolo Mella, a community with an active ferroalloy plant that produces very elevated air Mn levels; 2) Valcamonica, a region with slightly elevated air Mn levels due to a history of ferroalloy plant activity that ended in 2001, and; 3) Garda Lake, a reference region with background air Mn levels and no history of ferroalloy plant activity. The project will build upon the existing EU-funded PHIME (Public Health Impact of Mixed element Exposure in susceptible populations) study that has already examined a total of 300 children from Valcamonica and Garda Lake; we propose to enroll 450 more to achieve our aims. A strength of our proposal is the emphasis on environmental exposure assessment, utilizing measures of airborne Mn with 24 hr personal air monitors, Mn levels in home deposited dust, tap water, soil, and a detailed food frequency questionnaire, coupled with comprehensive cognitive, behavioral, motor, and sensory assessments, along with exposure biomarker measures (blood, urine, hair, nails) and Mn in shed deciduous teeth to assess early life and cumulative lifetime exposures. Preliminary results show changes in motor-coordination, odor identification and IQ among the residents in the historically exposed area of Valcamonica are associated with air Mn levels. This study will offer the unique opportunity to compare effects of Mn at distinct developmental time periods by evaluating children with three exposure histories 1) continuous high airborne Mn exposure since birth (Bagnolo Mella), 2) exposure to high air Mn levels over the first 3 - 5 postnatal years, but reduced current exposure (Valcamonica), and 3) no history of elevated airborne Mn exposure (Garda Lake). We will also address the role of genetic susceptibility to Mn via genetic variation in iron metabolism pathways genes. This will be the first study on Mn neurotoxicity in children supported by a profound characterization of environmental Mn exposure levels.